I try to implement web server for simple turn based game in WebAPI 2.0 using REST architecture. Although the gameplay itselfs (as it's purely turn based) seems to be a good candidate for web-api based server communication I have some concerns about "game-search" functionallity. When user want to start game, the GET request to "/api/gamesearch" would be made (and wait for next player) - but HTTP is stateless protocole so is it even possible to do that?
Another important thing (corellated with previous question) - I guess it's not possible to implement "game-over" functionallity when player (whose ture is atm) doesn't send any request (do not move) in some time period after HTTP response was send by server (which assigned ture to player) ?
I have seen there is a possibility to send Protocole exchange request for switching to WebSocket but that raises another question - do WebSockets need special web-server privileges (is pure mvc hosting enough?) - I have to keep costs low as much it is possible (that's personal project - I suspect I won't even earn penny on that).
You will probably need to communicate with your server throughout the game sessions as well. If your game is browser-based, something like SignalR should be great for your scenario. Usins SignalR you will be able to have constant communication with your server and your sever will be able to push data to your clients.
There shouldn't be a problem to use WebApi. Here you can find a discussion about WebApi and SignalR.
Related
Creating a user, adding some record to collection in the DB, updating some stuff, etc..
All of these we regularly do with HTTP requests against REST api.
Think about making Event bus as server instead of REST api.
In that method, create user will be an event name: "CreateUser" instead of REST api endpoint: POST /users.
In reflect to any action done in the event bus, it will re-emit a following event telling to any body needed to know about, that the event was done.
If for example someone viewing the vehicles collection and another user just edit one of the columns or add a new vehicle instance, it will be reflected immediately to who views it online.
My question is if there attitudes like I mentioned above, if there some formally names for it, if it a good practice, if you know someone who regularly uses it, a framework or something etc. Does the socket.io server can handle and behave like http server in high workloads?
You can use websockets for this; they provide a bidirectional channel between client and server to send messages across. You will have to catch and parse the messages on each end yourself, as there is no additional protocol on top of them.
They don't hold state, so there is no knowledge of who is looking at what, or who got what. You could send the same update message to all connected clients and leave it to the client to use it or not.
You would have to reprogram your client code and the API endpoints, because it's a different way of doing things, and it can also do server push.
I have no idea about frameworks though, as I always use them without one. Websockets are fast, but server behaviour at high workloads depends on implementation, and I only have experience with the websocket server I wrote myself. I suppose the performance of the socket.io can easily be googled.
I got a project using GWTP (which involves MVP separation, Gin and Dispatch), now I'm on the situation where it is required that changes on the server are pushed to specific clients
I've reading the gwt-comet and gwteventservice documentation, It seems the first doesn't work with RPC and the second Ecnapsulates RPC, for which I don't know how to fit it in my current command pattern from GWTP. Ideas?
I have been using gwt-comet (http://code.google.com/p/gwt-comet/). It's a native comet implementation working pretty good like RPC, you can send Strings or your GWT-serialized objects as well. And the best thing you don't need to do many things to make it works.
i used "Server Push in GWT" described here http://code.google.com/p/google-web-toolkit-incubator/wiki/ServerPushFAQ - it seemed to work fairly well for a small project.
This is really a servlet problem, not a GWT or GWTP problem.
So there are a few approaches to doing this, the most stable (in my opinion) is to have a long or blocking poll servlet. This is basically a servlet that is polled by the client, and holds the connection open for some period of time if there is no message to 'push' to the client, and if too much time passes (this is to get around http timeouts) a heartbeat is returned of some kind. Either way, when the servlet request request returns, the client just makes another request. This is the most portable and stable way to my mind, since it uses only the core servlet api, doesn't suffer from network issues, and the blocking portion allows you to have the poll 'park' at the server for some period of time and reduces total request load, while allowing very quick return of new information to the client when there is some available.
The next way to achieve this is via WebSockets, this is great once you get it working and in my opinion is the way of the future without question. I think this is a good one to work with since this will be, in my opinion, a paradigm shift in web applications once it catches a head of steam, so we all need to be up to speed. Basically, you have a javascript 'socket' open via port 80 (this is one of the best features, since you don't have to open any firewall holes) and can communicate in two directions across that socket.
Comet can also work, but it will generally lock you down to one server type, which may be alright for your application. Caveat here!!!! I have only done very small tests with comet, it was flaky for me when I set it up, and was not as steady as the blocking poll solution as I had it set up.
Now the neatest one in my opinion, but this one is very limited due to network constraints probably to single domain intranet applications, is to use an applet based push. This setup (which could be done with udp or a straight socket, I did all web just to keep it all simpler conceptually) takes the applet, uses it to spin up a jetty server instance on the client, and the has the page publish the client's jetty 'endpoint' to the server. At this point, the client can contact the server using it's servlets, and the server can contact the client at the servlet(s) exposed on the jetty server. This is true push, it's neato, but there are network nightmares.
So of all the above, I use long polling, keep my eye on web sockets since they are the future in my mind, and really like the applet based version, although it's quite restricted in use due to the network resolution limitations.
Once you have this decided, from GWTP you would just have actions or JSNI bridge methods as needed to connect to your server and receive responses. I won't go into this, since this is really a core servlet/http/javascript question more than a GWT or GWTP centric question.
I hope that helps!
I am trying to make the sync data application in which user have some value into the data base .And he have to send this data on to the server .With help http request how can i do that .
I need the
I am not using the php web server .
I am using the Normal HTTP web page .
ANd i have the some data in my iphone application and i want to Synchronization that data to server .
I it must check the Internet is available or not .If the Internet is ON than only he will Synchronization the data .that's my question .
Nothing else .You got my point or not .
I thing people will reply me soon please
Thanks
You have got to have some kind of server backend for synchronization of the local database. You can't do that using just the static HTML pages.
Your application and server have to have a way to talk to each other using a web service protocol, like SOAP or JSON/REST. Then your application has to translate the data from the database into such web service data objects.
Both your local database and the server (in case of more than one client) will have keep the records of at least the times of last synchronizations so both know what should be sent over the air in order to become in sync.
Also, in the usual case of more than one client, you have to solve the problem of conflicts resolution.
Web service versioning is important as well, as there will be very likely a need to improve the communication channel, maybe there will be changes in the database model to be synchronized.
As you can see, the idea of synchronizing local database to a server is not that simple, and if you think you can do it in a simple way, in time you'll realise that you're gradually reimplementing the aforementioned ideas.
Do a research on web service technologies, writing web services-aware apps, on synchronization with web services and on Reachability, for starters.
To check internet availability, check out the Reachability class from Apple. See this article.
To send data to a simple HTTP form via POST use NSURLConnection like in this article.
Cheers,
S
On this post, I read about the usage of XMPP. Is this sort of thing necessary, and more importantly, my main question expanded: Can a chat server and client be built efficiently using only standard HTTP and browser technologies (such as PHP and JS, or RoR and JS, etc)? Or, is it best to stick with old protocols like XMPP find a way to integrate them with my application?
I looked into CampFire via LiveHTTPHeaders and Firebug for about 5 minutes, and it appears to use Ajax to send a request which is never answered until another chat happens. Is this just CampFire opening a new thread on the server to listen for an update and then returning a response to the request when the thread hears an update? I noticed that they're requesting on a specific port (8043 if memory serves me) which makes me think that they're doing something more complex than just what I mentioned. Also, the URL requested started with /tcp/ which I found interesting.
Note: I don't expect to ever have more than 150 users live-chatting in all the rooms combined at the same time. I understand that if I was building a hosted pay for chat service like CampFire with thousands of concurrent users, it would behoove me to invest time in researching special technologies vs trying to reinvent the wheel in a simple way in my app.
Also, if you're going to do it with server polling, how often would you personally poll to maximize response without slamming the server?
The technology is broadly called Comet, which is supposedly some hilarious pun on Ajax1.
The XmlHTTPResponse variant seems to be the most popular.
The XHR version isn't strictly polling per se; as you said, the client connects with a long timeout and the server doesn't actually send a response until there is anything to send. Once the response is sent, it drops the connection and the client reconnects. They call it long polling, because the client is initiating the connection, but it differs from classic polling in that the client doesn't constantly connect requesting new content even if nothing has changed (i.e. no "is there a message now? no? how about now? what about now?")
It's more like trying to keep a constantly dropping connection open.
Yes it can absolutely be built using standard web technologies.
1I prefer to think of Ajax as a mighty Greek warrior rather than a cleaning product, so I frown mightily upon this pun.
That would first depend on your strategy of your webserver load balancing. 150 concurrent users that publish data over a stateless medium (HTTP) is certainly efficient with the bit of scripting (client- and server side). Remember that chat applications are just many client -> one server strategies, that fits perfectly over the web.
I'm looking for advice on the best way to implement some kind of bi-directional communication between a "server-side" application, written in Objective-C and running on a mac, and a client application running on an iPhone.
To cut a long story short, I'm adapting an existing library for use in a client-server environment. The library (which runs on the server) is basically a search engine which provides periodic results, and additionally can provide updates for any of those results at a later date. In an ideal world therefore I would be able to achieve the following with my hypothetical networking solution:
Start queries on the server.
Have the server "push" results to the client as they arrive.
Have the server "push" updates to individual results to the client as they arrive.
If I was writing this client to run on another Mac, I might well look at using Distributed Objects to mask the fact that the server was actually running remotely, but DO is not available on an iPhone.
If I was writing a more generic client-server application I would probably look at using HTTP to provide some kind of RESTful interface to searches, but this solution does not lend itself well to asynchronous updates and additionally what I am proposing does not fit well with the "stateless" tennet of REST: I would have to model my protocol so I "created" a search resource that I could subsequently query the state of and I would have to poll for updates to it.
One suggestion someone made was to make use of something like BLIP to provide me with a two-way pipe between the client and the server and implement my own "proxy" type objects for the server-side resources that knew how to fetch data from the server and additionally were addressable so that the server could push updates to them. Whilst BLIP provides the low-level messaging framework needed to communicate bi-directionally it still leaves me with a few questions:
How will I manage the lifetime of the objects on the server? I can have a message type that "creates" a search object, but when should that object be destroyed?
How well with this perform on an iPhone: if I have a persistent connection to the server will this drain the batteries too fast? This question is also pertinent in the HTTP world: most async updates are done using a COMET type hack which again requires a persistent connection.
So right now I'm still completely unsure what the best way to go is: I've done a lot of searching and reading but have not settled on any solution. I'm asking here on SO because I'm sure that there are many of you out there who have already solved this problem.
How have you gone about achieving real-time bidirectional networking between the iPhone and an Objective-C server-side app?